The Simple English Wiktionary has a definition for: twelve.

12 is a year in the 1st century. It was a leap year starting on Friday of the Julian calendar. At the time, it was known as the Year of the Consulship of Caesar and Capito.

• Annius Rufus is appointed Prefect of Judea.
• Germanicus and Gaius Fonteius Capito become Roman Consuls.
• Quirinius returns from Judea to become a counselor to Tiberius
• Ovid stops writing Fasti because of the lack of resources (being far from the libraries of Rome). He completes 6 books that detail festivals found in the Roman Calendar.
• October 12 – The Introduction of the so-called Criminal Tribes Act, 1871 was a continued discriminatory enactation on the 12th of October, in British India respectively.

• August 31 – Caligula, Roman Emperor